| 摘要 |
PURPOSE: To improve the contrast by a printer by subjecting a writing device to brightness modulation to form the composite exposure profile crossing a zerographic threshold in a process direction by the transition of an image. CONSTITUTION: The amplitude, duty cycle and/or pulse width of laser beam 13 are serially modulated (brightness modulation) on the basis of successive multibit digital data values. These data values respond to data clock pulses to be serially subjected to timing output from a buffer data source 23 and the data clock pulses are made synchronous to the scanning of a scanning spot from the bit map position in a raster scanning pattern to a bit map position with time. Therefore, data lock frequency can be selected so as to map data into the raster scanning pattern in desired magnification by using magnification same or different in a high speed scanning direction and a process direction. |
